1. Field of the Invention
The present invention relates to a method of producing an electrically conductive composite which is formed into various electrically conductive molded shapes.
2. Prior Art
In recent advanced electronics, shielding materials having lighter weight and higher electrical conductivity play an important role in shielding static electricity and electromagnetic liquids. The shielding materials include resin composites where metal powder, carbon powder, or fibers are mixed with plastics or rubber. Of these materials, resin composite with metal mixed therein is heavy and expensive. Electrically conductive materials of the carbon family are generally of lighter weight but are less conductive than those of the metal family. Thus, if a shielding-material having high electrical conductivity is to be made from particle like carbon materials, such as carbon black, more carbon material must be used to produce a unit amount of shielding material. A larger amount of carbon results in less machinability of the material and causes electrical conductivity to change due to shear force imposed on particle during milling or molding of the material. Therefore, it is difficult to obtain a shielding material with stable, uniform properties.
For higher electrical conductivity, resin composites have been proposed where rubber or plastics, for example, are mixed with electrically conductive materials such as graphitized carbon and graphite intercalated compounds obtained by mixing the graphitized carbon with metal salt, nitric acid, halogen, or alkali metals. However, these graphite intercalated compounds become generally unstable when heated and loses mechanical strength. They are decomposed or destroyed when they are milled with synthetic resin, making it difficult to produce resin composites having stable properties with good production repeatability.